Support is requested for continuation of studies in isolated perfused kidneys (and livers) concerning the interrelated physiology of renal vasoactive hormones, renal hemodynamics, and renal function. We propose to measure the effects of the renin angiotensin system, kallikrein-kinins, and prostaglandins on renal blood flow, its intrarenal distribution, salt and water excretion, and urinary concentration mechanisms. These studies will assess the integrated physiology of vasoactive hormonal control systems rather than isolated effects of single hormonal systems. Appropriate animal models have been selected for correlative studies in vivo of events which have been observed in isolated perfused kidneys.